My biggest pet peeve is when people have an issue that doesn't affect them so they need to declare it as "fake". Just because you don't feel the problem doesn't mean "it's a made up issue".
The following are simply facts:
1. In the US, among iPhone users, iMessage is by far the dominant messaging service.
2. Among certain socioeconomic groups in the US, iPhone is by far the dominant mobile phone. I have been in several friend groups where there was at most 1 other Android user.
3. In group chats, not only does the limited functionality for Android users make it harder to converse, but the presence of a single Android user can break the experience for everyone (I've had messages randomly not show up, abysmal video quality, etc.)
So while I would absolutely love it if other people would switch to Telegram or WhatsApp or whatever, you try telling a group of 10 people "Hey, can you all switch the messaging app you are familiar with and use all the time so I don't feel left out?" If you think that's viable you just don't understand human nature.
The other option is for Apple to simply make an Android version of iMessage (like all the other messaging apps you mentioned), but they don't seem too keen on that.
I do experience the human aspect, and have 4-5 different chat programs installed, which is not ideal, but it is just simply can’t be expected that everyone uses the same stuff. I just remember to use Telegram with friends X, Y and Signal with W.
It is still such a laughable issue from the POV of any other country.. SMS is there for text-only, it’s a legacy tech that didn’t ever get popular in different places due to it having shit support for non-ascii letters (writing a single ü would almost halve the remaining chars I can write), and not having unlimited SMS sends, so internet-based messaging spread like wide-fire. iMessage is the latter, the normal SMS is not. But there are also Telegram, Whatsapp, Facebook, a million other solutions.
It’s a made-up issue.